Sustainability of Organic, Conventional, and Integrated Apple Orchards

Abstract

Kathleen Delate summarized some of the farming systems studies that have been done and Kathleen Merrigan gave a good overview of some of the problems encountered in doing on-farm field research. I have been doing on-farm research for 20 years. The farming systems I have studied include organic, integrated, biodynamic, no-till, and conventional systems. Most of my studies deal with real farms, ranging from 2 to 500 ha in size. I either use the farms themselves as replicates, with two different farming systems or treatments represented, or I set up plots, that represent different farming systems or treatments, on a single commercial farm. I thought I would summarize the results of one of my studies that fits in the latter category. This on-farm study was published in Nature in 2001 (1) and examined organic, conventional, and integrated apple production systems for six growing seasons between 1994 and 1999. My research team wanted to look at a number of indicators of environmental and economic sustainability with these three apple production systems - the first objective of the study. These indicators included: (i) soil quality, including numerous physical, chemical, and biological properties; (ii) horticultural performance, including tree growth, yield, nutrients, fruit quality, storage potential, and sensory evaluations; (iii) profitability, including costs and gross and net returns; (iv) environmental impact; (v) energy efficiency; and (vi) pests, diseases, and disorders. For a second objective, we were interested in developing alternative practices for apple growers in Washington State who might like to convert to organic or integrated production. When we started the study in 1994, not even 1% of the growers were organic; today, about 6 to 7% are organic. We have about 170,000 acres in apples in the state. Apples are a significant crop in Washington State, which produces about 50% of all apples in the United States. Finally, a third objective was to help build a research base for organic production. Located on a 20-ha (50-acre) commercial apple orchard in the Yakima Valley of Washington State, a 1.7-ha (4-acre) study area was planted with ‘Golden Delicious’ apple trees in 1994 in a randomized complete-block design with four replications of three treatments: organic, conventional, and integrated. Each of the twelve experimental plots were 0.14 ha (0.33 acre) and consisted of four rows (spaced 1.4 m apart) each 80 trees (spaced 3.2 m) long trained on a three-wire trellis system for a density of 2240 trees/ha (903 trees/acre). The study was on-farm, grower/scientist managed. We have had three USDA grants for this project and we also have had the benefit of the farmer supplying the labor and most of the other inputs for the treatments, without which the study would not have been possible. In cooperation with the farmer, professional consultants, and extension agents, we chose appropriate management practices for the three systems. The organic system included compost and foliar sprays. In the first three years (1994-1996), bark mulch and landscape fabric controlled weeds; thereafter, cultivation and mowing were used for weed control. Organically certified biological controls, including applications of Bacillus thuringiensis and pheromone mating disruption to control codling moth (Cydia pomonella L.), were used for pest management. Fruit thinning was by hand. The conventional system included synthetic soil fertilizers and foliar sprays, pesticides, chemical fruit thinners, and pheromone mating disruption. The integrated system used both compost and synthetic fertilizers and controlled weeds with both bark mulch and herbicides. Pest management and fruit thinning were similar to those of the conventional system. The three systems had similar total soil N inputs. Pests, diseases, and physiological disorders were monitored throughout each growing season by the farmer and by professional consultants, who recommended organic, conventional, or integrated treatments for their control. More information on the study area and treatments as well as details of the analytical procedures were described in Reganold et al. (1). Organic matter was higher on the organic and integrated treatments because of the addition of compost. Any introductory soil science textbook will tell you the benefits of adding organic matter to the soil in your garden or farm. Instead of just reporting the data on the numerous soil quality properties, we used a soil quality index developed by a USDA scientist at Iowa State University. It was designed for corn and soybean systems. We modified it for apple production systems. The physical, chemical, and biological soil properties we examined, such as bulk density, water content, total nitrogen, nitrate-nitrogen, extractable phosphorus, cation exchange capacity, pH, electrical conductivity, organic carbon content, aggregate stability, microbial biomass carbon and nitrogen, and earthworm populations, were incorporated into a soil quality index. The index accounts for four functions of the soil (accommodating water entry, facilitating water movement and availability, resisting surface degradation, and sustaining fruit quality and productivity). Each of the functions receives a value of 25% or 0.25. Adding the four values together gives an index between 0 and 1, with 1 being the best. The soil quality indices were higher for the organic and integrated treatments for both 1998 and 1999. Because of poorer ability to accommodate water entry and to resist surface structure degradation, the conventional system (no organic amendments added) scored the lowest overall in soil quality. We looked at a number of horticultural parameters. We measured the size of the trees, and tree growth was identical for all three systems. We measured yields every year which is so important to growers. One of the main problems for organic apple production was that there were not any really good organically certified thinners for apples. In conventional or integrated systems, you can use chemical thinners that do a great job in maintaining similar yields every year. Because apples are bi-annual bearing, they tend to yield high one year and low the next. With the organic treatment, we had to hand thin because you cannot use those non-certified chemicals and there is not yet a good alternative on the market. In 1996, the conventional treatment had the highest yields, but in 1997 and 1998 the organic yielded more. Then, in 1999, the organic treatment had the lowest yields. However, when you add all those annual yields together - cumulative yields from 1995-1999 - there are no statistical differences in yields among the three systems. Maintaining equal organic yields with conventional yields is probably easier to do with horticultural crops than with grain crops. We also looked at fruit weight which gives you an indication of the size of the fruit. Usually the bigger the apple, the more money you get for the apple. In 1998 and 1999, organic apples were smaller than conventional and integrated apples. To an apple grower it is not financially beneficial to have to sell smaller apples. Another indication of quality is firmness of apples. Some apples are sold fresh after harvest and some are put in storage for up to six months to sell later. Sometimes they are in regular-atmosphere storage, but most often they are in controlled-atmosphere storage with carbon dioxide added. So, the data is for harvest, three months, and six months. And, apples have to meet a minimum firmness test at harvest or after storage to be sold as fresh apples rather than culled as juice or sauce. We found that the organic apples were either firmer or always as firm as the conventional and integrated apples. Growers and consumers generally like a Golden Delicious apple to be sweet. Ratios of soluble solids (sugar) content to acidity (tartness), an indication of sweetness, were most often highest in organic fruit. These data were confirmed in blind taste tests by untrained sensory panels (students, staff, and faculty at Washington State University) that found the organic apples to be sweeter after six months storage than conventional apples and less tart at harvest and after six months storage than conventional and integrated apples In 1995-1997, all marketed fruit produced from the three systems was sold for processing because it was downgraded primarily due to skin russetting, a physiological skin disorder that reduces the fruit's visual appeal but not its taste or other attributes. Although russetted Golden Delicious apples are not sold as fresh fruit in the US marketplace, Italy domestically markets a fully russetted Golden Delicious apple, and in the world market fully russetted Bosc pears are preferred to non-russetted ones. The low landscape position of the experimental site in the orchard resulted in early season cool, humid conditions that contributed to the unusually high level of russetting. Fruit damage due to other physiological disorders, pests, and diseases were minimal and equal for each of the three systems. In 1998 and 1999, marketable fruit not graded as Washington Extra Fancy or Fancy was sold for processing. Enterprise budgets were generated each year to calculate net returns from total costs and gross receipts. Receipts for the integrated system were estimated using prices for conventionally produced fruit, since unlike organic fruit there was no price premium for integrated fruit. Receipts for the organic system were estimated using prices for conventionally produced fruit in the first three years (1994-1996), the number of years necessary to transition from conventional to certified organic. The price premium to the grower for each grade of organic fruit in the next three years (1997-1999) averaged 50% above conventional prices. The three systems did not show a net annual profit until 1999 under measured fruit quality conditions (with skin russetting). When we adjusted the economic analysis by eliminating the effects of russetting but maintained the estimated crop loss of 15% due to other factors and the measured size, grade, and firmness of fresh fruit in this study, the organic system was more profitable than the conventional and integrated systems in 1997 and 1998. The breakeven point, when cumulative net returns equal cumulative costs, is projected to occur 9 years after planting for the organic system under measured fruit quality conditions. The conventional and integrated systems would break even 15 and 17 years after planting, respectively, under measured conditions. Under non-russetted fruit quality conditions, the breakeven point would occur 6, 8, and 9 years after planting for the organic, conventional, and integrated systems, respectively. Assuming similar non-russetted fruit quality conditions, estimated breakeven points for conventional apple orchards in central Washington range from 8 to 11 years from planting. The main reason the organic system can out-compete the conventional and integrated systems is that it has similar yields and receives a price premium for its fruit. Without price premiums for organic fruit, the conventional system would break even first, the integrated second, and the organic third under russetted or non-russetted fruit quality conditions. For breakeven points of the organic and integrated systems to occur in the same year as the conventional system, price premiums of 8.3% for the organic system and 2.2% for the integrated system would be necessary under measured fruit quality conditions. Under non-russetted fruit quality conditions, premiums of 14.1% for the organic system and 5.7% for the integrated system would be necessary to match the breakeven point of the conventional system. The biggest apple packer in Washington State is Stemilt Growers and they have developed an index, “Responsible Choice,” that measures the impact of pesticides on the environment. It takes into account for each pesticide the active ingredient, dose, application frequency, and targeted pest and is based on chemical efficacy, leaching potential, soil sorption index, chemical half-life, potential worker and consumer exposure, and effects on beneficial organisms of pesticides used in an orchard. The higher the rating, the greater the potential negative impact. Since only about 35% of conventional Washington growers in 1999 used pheromone-mating disruption (PMD), an environmentally benign biological control used in our conventional treatment, we also included a non-PMD conventional system in which synthetic pesticides were used in place of PMD. The total environmental impact rating of our conventional system was 6.2 times that of the organic system, whereas the integrated system rating was 4.7 times greater and the non-PMD conventional system rating was 7.7 times greater. We kept track of energy inputs and output from 1994-1999. This included labor, machinery, fuel, electricity, fertilizer, insecticides, fungicides, weed control, water, and infrastructure. Energy efficiency is expressed as an output/input ratio. You want the number to be larger rather than smaller. I thought these ratios would be pretty even across the three systems because apple production is an energy intensive system. The organic system, however, was about 7% more energy efficient than the conventional system and 5% more energy efficient than the integrated system.

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